Everything You Need to Know about Narcissists, Psychopaths, and Abuse - click on this link: http://www.narcissistic-abuse.com/faq1.html
To drive a motorcycle, let alone a truck one needs a license. To sell liquor, one better have a permit. But anyone can bring children to this world and raise them - narcissists and psychopaths included. Parenting requires no screening, no testing, no exams, and no licensing.
A parent diagnosed with full-fledged Narcissistic Personality Disorder (NPD) should be denied custody and be granted only restricted rights of visitation under supervision.
Narcissists accord the same treatment to children and adults. They regard both as sources of narcissistic supply, mere instruments of gratification - idealize them at first and then devalue them in favour of alternative, safer and more subservient, sources. Such treatment is traumatic and can have long-lasting emotional effects.
The narcissist's inability to acknowledge and abide by the personal boundaries set by others puts the child at heightened risk of abuse - verbal, emotional, physical, and, often, sexual. His possessiveness and panoply of indiscriminate negative emotions - transformations of aggression, such as rage and envy - hinder his ability to act as a "good enough" parent. His propensities for reckless behaviour, substance abuse, and sexual deviance endanger the child's welfare, or even his or her life.
(From the book "Malignant Self-love: Narcissism Revisited" by Sam Vaknin - Click on this link to purchase the print book, or 16 e-books, or 3 DVDs with 16 hours of video lectures on narcissists, psychopaths, and abuse in relationships: http://www.narcissistic-abuse.com/thebook.html)